The invention is a ballonet system for a lighter-than-air-vehicle, the vehicle having a lift producing gasbag and a longitudinal, vertical and lateral axis. In detail, the ballonet system includes a plurality of ballonets located within the gasbag positioned along the longitudinal axis and on each side of the vertical axis of the vehicle. Each of the ballonets include a flexible sheet joined at its periphery thereof to a portion of the wall of the gasbag. A ballonet pressurization system is coupled to each ballonet for pressurizing them with air that includes the portion of the wall of the gasbag forming the ballonet having a plurality of holes therethrough. A manifold having an inlet port is joined to the wall covering the holes therein and is adapted to diffuse the pressurized air entering therein. Also included is at least one fan having an inlet port coupled to ambient atmosphere and an outlet port coupled to the inlet port of the manifold for providing pressurized air to the interior thereof. A check valve located in the outlet port of the fan is provided for preventing air from flowing from the interior of the manifold out the inlet port of the fan. A ballonet venting system is included for venting the interior of the ballonet to ambient atmosphere.